The present invention comprises a new and distinct cultivar of a birch tree, botanically known as Betula papyrifera, and is hereto referred to by the cultivar name xe2x80x9cRencixe2x80x9d.
xe2x80x98Rencixe2x80x99 was discovered by the inventor in a group Betula papyrifera in a provenance test plot planted in Wooster, Ohio, in 1986. xe2x80x98Rencixe2x80x99 was originated from the open pollinated cross in a birch selection/breeding program in Wooster, Ohio. The non-patented female parent was Betula papyrifera as well as the male parent. xe2x80x98Rencixe2x80x99 was first noticed with a pyramidal growth habit, white, essentially non-exfoliating bark and a very high resistance to the Bronze Birch Borer. The growth habit renders it ideal for clumping. The first act of asexual reproduction of xe2x80x98Rencixe2x80x99 was accomplished by the inventor from the initial selection in our test plot on New Carlisle, Ohio. Currently, asexual reproduction is accomplished by micropropagation or tissue culture in Olympia, Wash. Horticultural examination of selected units has demonstrated that the combination of characteristics as herein disclosed for xe2x80x98Rencixe2x80x99 are firmly fixed and retained through its successive generations of asexual reproduction. xe2x80x98Rencixe2x80x99 has been observed in Sturgeon Bay, Wis. and New Carlisle, Ohio and characteristics have been stably maintained. The cultivar reproduces true to type. The new cultivar has not been observed under all possible environmental conditions. The phenotype may vary somewhat with variations in environment such as temperature, day length and light intensity, without a change in the genotype of a cultivar. The following observation, measurements, and comparisons describe the plants grown in New Carlisle, Ohio, and Sturgeon Bay, Wis. under natural field conditions which approximate those generally used in commercial growing operations.
The following traits have been repeatedly observed and are determined to be basic characteristics of xe2x80x98Rencixe2x80x99 which in combination distinguish this birch tree as a new and distinct cultivar:
1. Distinctive pyramidal growth habit with branching angles about 38-40xc2x0.
2. Bark color changes as the tree matures; from brown turning to only slightly exfoliating white bark.
3. Very high resistance to the Bronze Birch Borer.
4. Rapid growth rate.
The new cultivar can be compared to nonpatented Betula papyrifera. The nonpatented plants have a loose oval growth habit and white exfoliating bark. They have variable resistance to the Bronze Birch Borer. The numbered traits above clearly distinguish the new cultivar from nonpatented Betula papyrifera.